Heat exchanger for use with earth-coupled air conditioning systems

ABSTRACT

An air handling system that includes at least one earth-coupled heat exchanger assembly that further includes a first pipe section having an inner diameter and an outer diameter; a second pipe section concentrically surrounding a portion of the first pipe section, wherein the second pipe section includes an inner diameter and an outer diameter, wherein the outer diameter of the first pipe section and the inner diameter of the second pipe section define a space therebetween, and wherein the space between the first pipe section and the second pipe section is evacuated to form an insulating vacuum therein; and a third pipe section concentrically surrounding a portion of the second pipe section, wherein the third pipe section includes an inner diameter and an outer diameter, and wherein the outer diameter of the second pipe and the inner diameter of the third pipe section define a passageway therebetween.

This patent application is a continuation of U.S. patent applicationSer. No. 15/173,077 filed on Jun. 3, 2016 and entitled “Heat Exchangerfor Use with Earth-Coupled Air Conditioning Systems”, the disclosure ofwhich is hereby incorporated by reference herein in its entirety andmade part of the present U.S. utility patent application for allpurposes.

BACKGROUND OF THE INVENTION

The described invention relates in general to air handling and airconditioning systems, devices, and methods, and more specifically to anair handling system that includes a plurality of earth-coupled heatexchangers that increase system efficiency.

Earth-coupled or ground-coupled heating and cooling systems are widelyutilized for efficiently providing environmental heating and cooling orprocess heating and cooling. A primary advantage of earth-coupledsystems is the relatively constant temperature of subsurface soil, whichprovides a readily accessible source/sink for heating and coolingequipment. There are two basic types of earth-coupled systems. A firstgeneral type of system utilizes water source heat pump units that areconnected to either ground water or other bodies of water that arepumped through the units to provide the source/sink for the units.Another variation of this earth-coupled system is a closed loop withpiping extending down into wells bored into the earth or laid in shallowditches and covered with earth. These systems can utilize either wateror antifreeze as a transfer medium. The second general type of system isreferred to as direct-coupled. A direct-coupled system utilizesrefrigerant piping directly inserted into wells similar to the closedloop water system previously described.

A significant disadvantage of well systems such as those described aboveis that these systems require piping to be installed with down pipes andrisers together in a common well. When installed in this manner, thepipes transfer heat to each other along with the surrounding earth. Heattransfer between the pipes reduces total heat transfer to the earth and,therefore, requires more wells or deeper wells to achieve the desiredheat transfer to the soil. Therefore, the net effect caused by two pipestransferring heat to each other is a reduction in the efficiency of thesystem, thus requiring a larger and more expensive heat exchanger to beinstalled. Accordingly, there is an ongoing need for a highly efficient,cost-effective heat exchanger for use with earth-coupled heating andcooling systems.

SUMMARY OF THE INVENTION

The following provides a summary of certain exemplary embodiments of thepresent invention. This summary is not an extensive overview and is notintended to identify key or critical aspects or elements of the presentinvention or to delineate its scope.

In accordance with one aspect of the present invention, a firstair-handling system is provided. This air handling system includes atleast one earth-coupled heat exchanger assembly, wherein the at leastone earth-coupled heat exchanger assembly includes a first pipe sectionhaving an inner diameter and an outer diameter; a second pipe sectionconcentrically surrounding a portion of the first pipe section, whereinthe second pipe section has an inner diameter and an outer diameter,wherein the outer diameter of the first pipe section and the innerdiameter of the second pipe section define a space therebetween, andwherein the space between the first pipe section and the second pipesection is evacuated to form an insulating vacuum therein; and a thirdpipe section concentrically surrounding a portion of the second pipesection, wherein the third pipe section has an inner diameter and anouter diameter, and wherein the outer diameter of the second pipe andthe inner diameter of the third pipe section define a passagewaytherebetween.

In accordance with another aspect of the present invention, a secondair-handling system is provided. This air handling system includes aplurality of earth-coupled heat exchanger assemblies each of whichincludes a first pipe section having an inner diameter and an outerdiameter; a second pipe section concentrically surrounding a portion ofthe first pipe section, wherein the second pipe section has an innerdiameter and an outer diameter, wherein the outer diameter of the firstpipe section and the inner diameter of the second pipe section define aspace therebetween, and wherein the space between the first pipe sectionand the second pipe section is evacuated to form an insulating vacuumtherein; and a third pipe section concentrically surrounding a portionof the second pipe section, wherein the third pipe section has an innerdiameter and an outer diameter, and wherein the outer diameter of thesecond pipe and the inner diameter of the third pipe section define apassageway therebetween; a plurality of individual liquid lines, whereineach line is connected to the first pipe section of an earth-coupledheat exchanger assembly; and a plurality of hot gas suction lines,wherein each line is connected to the third pipe section of anearth-coupled heat exchanger assembly and is communication with thepassageway formed between the outer diameter of the second pipe and theinner diameter of the third pipe section

In yet another aspect of this invention, a third air handling system isprovided. This air handling system includes a plurality of earth-coupledheat exchanger assemblies, each of which includes a first pipe sectionhaving an inner diameter and an outer diameter, wherein the first pipesection further includes a gas expansion device attached to the bottomportion thereof; a second pipe section concentrically surrounding aportion of the first pipe section, wherein the second pipe section hasan inner diameter and an outer diameter, wherein the outer diameter ofthe first pipe section and the inner diameter of the second pipe sectiondefine a space therebetween, and wherein the space between the firstpipe section and the second pipe section is evacuated to form aninsulating vacuum therein; and a third pipe section concentricallysurrounding a portion of the second pipe section, wherein the third pipesection has an inner diameter and an outer diameter, and wherein theouter diameter of the second pipe and the inner diameter of the thirdpipe section define a passageway therebetween; a plurality of individualliquid lines, wherein each line in the plurality of individual liquidlines is connected to the first pipe section of an earth-coupled heatexchanger assembly at one end thereof and to a solenoid valve at theother end thereof, wherein each solenoid valve is connected to amanifold, wherein the manifold is connected to a main liquid line, andwherein the main liquid line is connected to the coil of an indoor airconditioning unit; and a plurality of hot gas suction lines, whereineach line in the plurality of hot gas suction lines is connected to thethird pipe section of an earth-coupled heat exchanger assembly and iscommunication with the passageway formed between the outer diameter ofthe second pipe and the inner diameter of the third pipe section,wherein each hot gas suction line is connected to a main hot gas suctionline, and wherein the main hot gas suction line is connected to acompressor.

Additional features and aspects of the present invention will becomeapparent to those of ordinary skill in the art upon reading andunderstanding the following detailed description of the exemplaryembodiments. As will be appreciated by the skilled artisan, furtherembodiments of the invention are possible without departing from thescope and spirit of the invention. Accordingly, the drawings andassociated descriptions are to be regarded as illustrative and notrestrictive in nature.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a partof the specification, schematically illustrate one or more exemplaryembodiments of the invention and, together with the general descriptiongiven above and detailed description given below, serve to explain theprinciples of the invention, and wherein:

FIG. 1 is a schematic of an air handling system in accordance with anexemplary embodiment of the present invention, wherein the system isoperating in cooling mode;

FIG. 2 is a schematic of an air handling system in accordance with anexemplary embodiment of the present invention, wherein the system isoperating in heating mode;

FIG. 3 is a cross-sectional side view of a heat exchanger assembly inaccordance with an exemplary embodiment of the present invention; and

FIG. 4 is a cross-sectional top view of the heat exchanger of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary embodiments of the present invention are now described withreference to the Figures. Reference numerals are used throughout thedetailed description to refer to the various elements and structures.Although the following detailed description contains many specifics forthe purposes of illustration, a person of ordinary skill in the art willappreciate that many variations and alterations to the following detailsare within the scope of the invention. Accordingly, the followingembodiments of the invention are set forth without any loss ofgenerality to, and without imposing limitations upon, the claimedinvention.

The present invention provides systems and devices for improving heattransfer in earth-coupled exchange systems commonly referred to asgeothermal heating systems. Such systems are actually geo-exchangesystems that utilize the relatively constant temperatures found in thesoil below the surface of the earth. This invention permits a greatlyreduced heat transfer to occur between the two pipes by disposing onepipe within the other pipe with the region between the two pipesevacuated to a vacuum. By way of comparison, the vacuum condition thatexists between the two pipes reduces conductive heat transfer in thesame manner that a thermos bottle reduces heat transfer. The ability tomaintain a near perfect vacuum in the region between the two pipesimproves the efficiency of the heat exchange to the earth. The highlyefficient design of this invention also allows the system to operatewith much greater temperature differentials than are normally associatedwith geo-exchange systems, thereby permitting a much smaller, lessexpensive system to provide capacity equivalent to larger, moreexpensive systems.

With reference to the Figures, FIG. 1 depicts an exemplary embodiment ofthe heating system of the present invention in its cooling mode and FIG.2 depicts the same system in its heating mode. In both FIG. 1 and FIG.2, air handling system 100 includes air conditioning unit 200, whichfurther includes indoor unit 202 that houses coil 204 and expansiondevice or valve 206, to which main liquid line 300 is connected.Manifold 302 is connected to main liquid line 300 and further includes aplurality of in-line solenoid valves 304 to which individual liquidlines 306 are connected. Suction flow line 400 is connected torefrigerant reversing valve 402, accumulator 404, and compressor 406.Compressor 406 is also connected to hot gas flow line 408, which isconnected to a plurality of individual hot gas/suction lines 410. Eachindividual liquid line 306 and individual hot gas/suction line 410 isconnected to an individual heat exchanger assembly 500. As described ingreater detail below, in FIGS. 1-2, the direction of refrigerant and/orhot gas flow is indicated by arrows A and B (FIG. 1) and C and D(FIG.2).

Each individual heat exchanger assembly 500 includes multiple pipesections, which are concentrically arranged with regard to one another.With reference to FIGS. 3 and 4, the innermost pipe section in each heatexchanger assembly 500 is first pipe section 510, which is connected toan individual liquid line 306 at its upper end and an expansiondevice/piston assembly 512 at its lower end. First pipe section 510 isdisposed within second pipe section 520, which surrounds a portion offirst pipe section 510 and which is connected thereto at its lower endby connector 522. Because the outer diameter of first pipe section 510is smaller than the inner diameter of second pipe section 520, acylindrical space or region 524 is formed between these two pipesections. Air in region 524 is evacuated to create an insulating vacuumbetween first pipe section 510 and second pipe section 520. A portion ofsecond pipe section 520 is disposed within third pipe section 530.Connector 532 seals the upper portion of third pipe section 530 and cap534 seals the lower portion of third pipe section 530. Connector 532also attaches to an individual hot gas/suction line 410. Because theouter diameter of second pipe section 520 is smaller than the innerdiameter of third pipe section 530, a cylindrical space or region 536 isformed between these two pipe sections. This space or region providespassage 536 for a refrigerant (as a hot gas) to flow within heatexchanger assembly 500. Each heat exchanger assembly 500 includes atleast one spacer 540 for maintain the proper distance between the threepipe sections and adding structural stability to the heat exchangerassembly.

Each heat exchanger assembly 500 utilizes refrigerant to transfer heatdirectly to or from the earth and the concentric design of each heatexchanger assembly 500 allows third pipe section 530, which is theoutermost pipe section, to directly contact the earth when properlyinstalled. In an exemplary embodiment, each pipe section is constructedfrom ACR (air conditioning and refrigeration field services) copper pipeand fittings. For example, in an exemplary embodiment, first pipesection 510 is constructed from ⅜ inch ACR copper pipe; second pipesection 520 is constructed from ⅞ inch ACR copper pipe; and third pipesection 530 is constructed from 1 and ⅛ inch ACR copper pipe. In someembodiments, hot gas/suction passage 536 is enhanced through theplacement of a spiral structure or device 537 therein, which causes therefrigerant to move through passage 536 in a swirling motion. Thisswirling motion or swirling action causes a turbulent gas flow to occurand increases the heat transfer path length as the refrigerant flowsthrough heat exchanger assembly 500. The spiral structure may be formedaround the inner diameter of third pipe section 530 from the material ofthe pipe, or the spiral structure may be a separate component that isinserted into the interstitial space between second pipe section 520 andthird pipe section 530. Refrigerant passing through outer or third pipesection 530 enters heat exchanger assembly 500 at the top portionthereof as high temperature, high pressure gas, or enters at the bottomthrough expansion device/piston assembly 512 as low temperature, lowpressure gas. First pipe section 510, which is the smallest andinnermost pipe section conveys liquid refrigerant through heat exchangerassembly 500, with the direction of the flow being determined by themode of operation of the system (i.e., either heating or cooling), asdescribed in greater detail below.

With reference to FIG. 1, when air handling system 100 is operating incooling mode as a cooling unit, high-pressure liquid refrigerant travelsupward through first pipe section 510 to expansion valve 206 (located atcoil 204 of indoor unit 202), where it becomes a low-pressure,low-temperature gas. After passing through expansion valve 206, thislow-pressure, low-temperature gas absorbs heat from the air to be cooledor process to be cooled, thereby providing the desired cooling effect.The low-pressure gas then enters compressor 406, where it is compressedto high-temperature, high-pressure gas. This high-pressure,high-temperature gas then travels through hot gas flow line 408 andindividual hot gas/suction lines 410 to heat exchanger assemblies 500.The high-pressure, high-temperature gas then travels downward throughhot gas/suction passage 536 and transfers heat to the soil surroundingthe exterior of third pipe section 530. Vacuum space 524 reduces heattransfer between hot gas/suction passage 536 and first pipe section 510,which is the passageway for the liquid refrigerant. When thehigh-pressure, high-temperature gas reaches the bottom area of heatexchanger assembly 500, the gas has condensed into high-pressure,low-temperature liquid refrigerant. The liquid refrigerant then bypassesexpansion device/piston assembly 512 and enters first pipe section 510.The entire process then repeats.

With reference to FIG. 2, when air handling system 100 is operating inheating mode as a heating unit, high-pressure liquid refrigerant travelsfrom coils 204 of indoor unit 202 through main liquid line 300, manifold302, solenoid valves 304, and individual liquid lines 306 to pluralityof heat exchanger assemblies 500. The high-pressure liquid refrigeranttravels then travels downward through first pipe section 510 to thebottom portion of each heat exchanger assembly 500 where it then passesthrough expansion device/piston assembly 512. After passing throughexpansion device/piston assembly 512, the refrigerant enters hotgas/suction passage 536 as low-pressure, low-temperature gas. Thislow-pressure, low-temperature gas then travels up through hotgas/suction passage 536 and absorbs heat from the surrounding earth.Vacuum space 524 reduces heat transfer between hot gas/suction passage536 and first pipe section 510. Warmed low-pressure gas then travels tothe suction inlet of compressor 406 where it is compressed intohigh-temperature, high-pressure gas. This hot gas then travels to coils204 of indoor unit 202 where it transfers heat to the air or a processbeing heated and effectively heats the space or process conditioned byindoor unit 202 while condensing into high-pressure liquid. The cycle isthen complete and the entire process repeats.

The two modes of operation discussed above, i.e., heating and cooling,are commonly associated with heat pumps, which are utilized for heatingand cooling of interior spaces. The advantage of earth-coupled systemsis the increased efficiency that results from utilizing the stabletemperatures of the earth at depths deeper than about four feet belownormal grade. Air handling or air conditioning systems that utilizewells or horizontal water-based apparatuses require considerablephysical space and more material is necessary for achieving the systemcapacity required for most residences or other structures. Increasedspace requirements and greater required depths for wells results inincreased costs and extends the period of time required to recoverinstallation and materials costs based on added or increased systemefficiency. Accordingly, such additional expenses often prevent an airhanding installation from being cost-effective at all unless energy costare truly excessive. Improving the efficiency of an earth-coupled heatexchanger permits a reduction in overall size of the system wheninstalled and reduces the cost of the required installation.

With regard to the present invention, and as shown in FIGS. 1-2, anexemplary system installation includes a common hot gas/suction line408, which serves a plurality of earth coupled heat exchanger assemblies500, as well as individual liquid lines 306 connected to each heatexchanger assembly 500. This configuration permits heat exchangerassemblies 500 to be activated individually. Individual liquid lines 306are connected to manifold 302, which includes electrically operatedsolenoid valves 304 that are used to select which heat exchangerassemblies 500 are active at any given time. The ability to select thenumber of heat exchanger assemblies 500 that are active can be used forload matching and performance optimization. If a compressor unit is usedthat includes part load capacity control such as a variable speedcontrol or other method for part load operation, the number of activeheat exchanger assemblies 500 can be selected to match the actual systemload. Assuring that there are more heat exchanger assemblies 500installed than are actually required for the maximum anticipated load,provides at least one inactive heat exchanger assembly 500 at all times.This arrangement permits system 100 to use a rotating sequence foroptimizing system performance based on temperatures measured from eachheat exchanger assembly 500.

Temperature sensors are typically installed on individual liquid lines306 for monitoring the performance of each heat exchanger assembly 500.System 100, which includes a controller (not shown in the Figures),determines the least effective heat exchanger assembly 500 using atime-based algorithm and when that particular heat exchanger assemblypasses a pre-determined threshold, system 100 takes that unit offlineand a unit that was previously taken offline is then reactivated. Thissequence optimizes the performance of system 100 by providing the earthsurrounding each heat exchanger assembly 500 with a rest period torecover during peak periods of operation.

While the present invention has been illustrated by the description ofexemplary embodiments thereof, and while the embodiments have beendescribed in certain detail, there is no intention to restrict or in anyway limit the scope of the appended claims to such detail. Additionaladvantages and modifications will readily appear to those skilled in theart. Therefore, the invention in its broader aspects is not limited toany of the specific details, representative devices and methods, and/orillustrative examples shown and described. Accordingly, departures maybe made from such details without departing from the spirit or scope ofthe general inventive concept.

1. An air handling system, comprising: (a) at least one earth-coupledheat exchanger assembly, wherein the at least one earth-coupled heatexchanger assembly is adapted to be buried in the earth and includes:(i) a first pipe section, wherein the first pipe section includes aninner diameter and an outer diameter; (ii) a heat-transfer reducinginsulator that includes a second pipe section concentrically surroundinga portion of the first pipe section, wherein the second pipe sectionincludes an inner diameter and an outer diameter, wherein the outerdiameter of the first pipe section and the inner diameter of the secondpipe section define a space therebetween, wherein the space between thefirst pipe section and the second pipe section is evacuated to form aninsulating vacuum therein, and (iii) a third pipe section concentricallysurrounding a portion of the second pipe section, wherein the third pipesection includes an inner diameter and an outer diameter, and whereinthe outer diameter of the second pipe and the inner diameter of thethird pipe section define a passageway therebetween, (iv) wherein theheat-transfer reducing insulator is operative to reduce heat transferbetween the first pipe section and the third pipe section and improveefficiency of heat transfer between the third pipe section and theearth.
 2. The system of claim 1, further comprising a gas expansiondevice connected to the first pipe section at the bottom portionthereof.
 3. The system of claim 1, further comprising aturbulence-inducing spiral structure disposed within the third pipesection.
 4. The system of claim 1, further comprising a stabilizingspacer disposed within the third pipe section.
 5. The system of claim 1,further comprising a plurality of individual liquid lines, wherein eachline in the plurality of individual liquid lines is connected to thefirst pipe section of an earth-coupled heat exchanger assembly.
 6. Thesystem of claim 5, further comprising a solenoid valve connected to eachindividual liquid line upstream from each earth-coupled heat exchangerassembly.
 7. The system of claim 6, wherein each solenoid valve isconnected to a manifold, wherein the manifold is connected to a singleliquid line, and wherein the single liquid line is connected to the coilof an indoor air conditioning unit.
 8. The system of claim 1, furthercomprising a plurality of hot gas suction lines, wherein each line inthe plurality of hot gas suction lines is connected to the third pipesection of an earth-coupled heat exchanger assembly and is communicationwith the passageway formed between the outer diameter of the second pipeand the inner diameter of the third pipe section.
 9. The system of claim8, wherein each hot gas suction line is connected to a main hot gassuction line, and wherein the main hot gas suction line is connected toa compressor.
 10. An air handling system, comprising: (a) a plurality ofearth-coupled heat exchanger assemblies, wherein each earth-coupled heatexchanger assembly in the plurality of earth-coupled heat exchangerassemblies is adapted to be buried in the earth and includes: (i) afirst pipe section, wherein the first pipe section includes an innerdiameter and an outer diameter; (ii) a heat-transfer reducing insulatorthat includes a second pipe section concentrically surrounding a portionof the first pipe section, wherein the second pipe section includes aninner diameter and an outer diameter, wherein the outer diameter of thefirst pipe section and the inner diameter of the second pipe sectiondefine a space therebetween, and wherein the space between the firstpipe section and the second pipe section is evacuated to form aninsulating vacuum therein; and (iii) a third pipe section concentricallysurrounding a portion of the second pipe section, wherein the third pipesection includes an inner diameter and an outer diameter, and whereinthe outer diameter of the second pipe and the inner diameter of thethird pipe section define a passageway therebetween, wherein theheat-transfer reducing insulator is operative to reduce heat transferbetween the first pipe section and the third pipe section and improveefficiency of heat transfer between the third pipe section and theearth; (b) a plurality of individual liquid lines, wherein each line inthe plurality of individual liquid lines is connected to the first pipesection of an earth-coupled heat exchanger assembly; and (c) a pluralityof hot gas suction lines, wherein each line in the plurality of hot gassuction lines is connected to the third pipe section of an earth-coupledheat exchanger assembly and is communication with the passageway formedbetween the outer diameter of the second pipe and the inner diameter ofthe third pipe section.
 11. The system of claim 10, further comprising agas expansion device connected to the first pipe section at the bottomportion thereof.
 12. The system of claim 10, further comprising aturbulence-inducing spiral structure disposed within the third pipesection.
 13. The system of claim 10, further comprising a stabilizingspacer disposed within the third pipe section.
 14. The system of claim10, further comprising a solenoid valve connected to each individualliquid line upstream from each earth-coupled heat exchanger assembly.15. The system of claim 14, wherein each solenoid valve is connected toa manifold, wherein the manifold is connected to a single liquid line,and wherein the single liquid line is connected to the coil of an indoorair conditioning unit.
 16. The system of claim 10, wherein each hot gassuction line is connected to a main hot gas suction line, and whereinthe main hot gas suction line is connected to a compressor.
 17. An airhandling system, comprising: (a) a plurality of earth-coupled heatexchanger assemblies, wherein each earth-coupled heat exchanger assemblyin the plurality of earth-coupled heat exchanger assemblies is adaptedto be buried in the earth and includes: (i) a first pipe section,wherein the first pipe section includes an inner diameter and an outerdiameter, and wherein the first pipe section further includes a gasexpansion device attached to the bottom portion thereof; (ii) aheat-transfer reducing insulator that includes a second pipe sectionconcentrically surrounding a portion of the first pipe section, whereinthe second pipe section includes an inner diameter and an outerdiameter, wherein the outer diameter of the first pipe section and theinner diameter of the second pipe section define a space therebetween,and wherein the space between the first pipe section and the second pipesection is evacuated to form an insulating vacuum therein; and (iii) athird pipe section concentrically surrounding a portion of the secondpipe section, wherein the third pipe section includes an inner diameterand an outer diameter, and wherein the outer diameter of the second pipeand the inner diameter of the third pipe section define a passagewaytherebetween, wherein the heat-transfer reducing insulator is operativeto reduce heat transfer between the first pipe section and the thirdpipe section and improve efficiency of heat transfer between the thirdpipe section and the earth; (b) a plurality of individual liquid lines,wherein each line in the plurality of individual liquid lines isconnected to the first pipe section of an earth-coupled heat exchangerassembly at one end thereof and to a solenoid valve at the other endthereof, wherein each solenoid valve is connected to a manifold, whereinthe manifold is connected to a main liquid line, and wherein the mainliquid line is connected to the coil of an indoor air conditioning unit;and (c) a plurality of hot gas suction lines, wherein each line in theplurality of hot gas suction lines is connected to the third pipesection of an earth-coupled heat exchanger assembly and is communicationwith the passageway formed between the outer diameter of the second pipeand the inner diameter of the third pipe section, wherein each hot gassuction line is connected to a main hot gas suction line, and whereinthe main hot gas suction line is connected to a compressor.
 18. Thesystem of claim 17, further comprising a turbulence-inducingspiral-shaped structure disposed within the third pipe section.
 19. Thesystem of claim 17, further comprising a stabilizing spacer disposedwithin the third pipe section.
 20. The system of claim 17, wherein eachearth-coupled heat exchanger assembly is adapted to be operatedseparately from the other earth-coupled heat exchanger assemblies.